Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

This mission was the seventh Soviet attempt to recover soil samples from the surface of the Moon and the first after the success of Luna 16.

After two midcourse corrections on 4 and 6 September 1971, Luna 18 entered a circular orbit around the Moon on 7 September at 100 kilometers altitude with an inclination of 35°. After several more orbital corrections, on 11 September, the vehicle began its descent to the lunar surface.

Unfortunately, contact with the spacecraft was abruptly lost at 07:48 UT at the previously determined point of lunar landing. Impact coordinates were 3°34' north latitude and 56°30' east longitude, near the edge of the Sea of Fertility. Officially, the Soviets announced that "the lunar landing in the complex mountainous conditions proved to be unfavorable." Later, in 1975, the Soviets published data from Luna 18's continuous-wave radio altimeter that determined the mean density of the lunar topsoil.

Key Dates

2 Sep 1971: Launch

7 Sep 1971: Lunar Orbit Insertion

11 Sep 1971: Crashed on the Moon

Status: Unsuccessful

Fast Facts

This was the Soviet Union's seventh attempt to robotically gather samples from the lunar surface.

The Soviets said it crashed in "unfavorable" mountainous terrain.

The spacecraft did return information on lunar soil density before it crashed.